In a semiconductor device, a plurality of semiconductor chips are stacked on each other and a three-dimensional structure is provided. Using such a three-dimensional structure, miniaturization and high density of the semiconductor device can be achieved. The semiconductor chips, which are vertically stacked, are electrically connected to each other by, for example, a TSV (Through Silicon Via) provided in the semiconductor chip.
The TSV is formed at a wafer level, for example, before the semiconductor substrate is diced into individual chips. In order to achieve the semiconductor device of the three-dimensional structure at low cost, it is preferable to stably form the TSV in the semiconductor chip.